Improvement in boiler-furnaces



L. STEVENS.

Boiler-Furnaces.

Patented July 14,1874.

NITED lST-Afrns PATENT OFFICE.

LnvI sTnvnNs, oF WASHINGTON, DISTRICT ou COLUMBIA.

lMPRQvsMl-:NT IN BoiiER-,FuRNAcEa Specification forming part of Letters Patent No.153`,123, dated July 14, 1874; application filed V December l, 1873.

CASE B.

To all whom it may concern:

Be it known that I, LEVI STEVENS, of Vashington city, in the county of Washington and District of Columbia, have invented certain Improvements in Boiler Furnaces, of which the following is a specification:

My invention consists in an apparatus in which the products of combustion are taken from the rear end of the fire-box, combined with steam and atmospheric air, and again introduced into the fire-box, the object being to cause a perfect combustion of the fuel, and to avoid the production of smoke; this apparatus being intended for more perfectly carrying out the method or process of utilizing fuel in furnaces for which I filed an application for a patent July 15, 1873.

Figure l is a top-plan view of my apparatus as it appears under the boiler, portions being broken away to show dierent parts. Fig. 2 is a longitudinal vertical section through the apparatus, on the line x of Fig. l. Fig. 3 is a front view of the fire-box.

In the drawing, A represents the fire-box or combustion-chamber of a common horizontal boiler; B, the usual fire-grate and G, the bridgawall at the back end of the grate. The bridge-wall is constructed with an interior chamber, D, which has a top opening or inlet, a, and two front openings, b, the latter opening into the ash-pit, or space below the gratebars B. Two large tubes, H, pass lengthwise through the ash-pit, opening at their forward ends into the air and at their inner ends into the chamber D, for the purpose of admitting atmospheric air into said chamber. In order to regulate the admission of air, the tubes H are provided at their forward ends with registers or dampers I, as shown. A superheater, E, consisting of an iron body containing a zigzag passage, is mounted at the rear end and in the middle of the fire-grate, as shown in Figs. l and 2. Steam from the boiler is introduced through a pipe, J, into the superheater, from whence it is discharged through two branch pipes, F, which pass into the chamber D, and terminate in nozzles c, 1ocated in the respective openings b, and directed toward the ash-pit, as shown in Figs. l and 2.

The operation of the apparatus is as follows: Steam from the boiler passes through the pipe J into the superheater E, and, after being raised to a very high temperature therein, blows forward in strong jets from the nozzles c into the ash-pit. The steam-jets cause a strong draft or suction through the holes b into the ash-pit from the chamber D, thereby drawing the products of combustion from the re-box through the opening a, and atmospheric air through the pipes H into the said chamber D, and thence into the ashpit, whence the air, products of combustion, and superheated steam, thoroughly mingled with each other, pass up through the grate-bars into the fire-box, where they are consumed. The compound consisting of the three elements named, and heated, as it is, to a very high temperature, is highly combustible, and, in connection with the coal or other fuel on the grate, produces an intense fire. By means of the dampers I, the admission of atmospheric oxygenlnay be controlled with great nicety, and by means of a cock, suitably applied, the admission of steam may also be controlled with like precision, and thus the relative quantity of the three elements so regulated as to render the combustion almost perfect.

It is obvious that the form and arrangement of the parts may be varied without departing from the spirit of the invention, the essential requisite being that the gases -of combustion shall be taken from the rear end of the fire-chamber or grate, instead of from the front end, and, after being mixed with the air and steam, be injected under the grate from the rear, instead of from the front. The air may be taken in at the sides into chamber D, thus dispensing with the tubes H; but I prefer to use them located in the ash-pit, because, rst, the inowing air is heated somewhat; and, second, because they are easily applied to furnaces already built. So, too, instead of the chamber D and the inlet a for the gases, tubes may be substituted, as shown in my former application; but I prefer the arrangement shown, because the chamber D affords a better means of more thoroughly commingling the gases and air, and at a higher heat, before introducing them with the steam into the furnace. The superheater may be dispensed with, and the steam used Without being super heated, but Without as good results.

I do not in this application make any claim to the method of utilizing the fuel by combining gases from the fire-chamber with steam, Whether superheated or not, with or Without air, as that is fully set forth and claimed in a prior application, filed July l5, 1873--this being an improvement in the apparatus used for carrying out or applying the said method.

And now, having described my improved apparatus, what I do claim is- Y Y 1. In combination with a furnace, a chamber, D, provided with inlets or passages to admit the hot gases from the fire-chamber, and also air from the exterior7 and having steam-` LEVI STEVENS.

i Witnesses J. MCKENNE Y, W. C. DODGE. 

